Multi-span greenhouse ventilation and cooling systems maintain optimal growing conditions. Continuous ridge vents provide natural ventilation across large spans. Exhaust fans create negative pressure for forced ventilation. Evaporative cooling pads lower temperatures by 10-15 degrees. Fogging systems provide fine water droplets for rapid cooling. Horizontal air flow fans distribute air evenly throughout the structure. Automated controls coordinate multiple cooling methods. Proper ventilation prevents humidity buildup and disease. Adequate air exchange ensures CO2 replenishment for photosynthesis.